This invention relates to improvements in and concerning a grommet seal made of a thermoplastic resin.
It has heretofore been proposed, as in U.S. Pat. Nos. 684,909; 2,974,186; 3,091,795; 3,193,613; 3,701,505; 4,089,496 and 4,137,602, to provide devices variously referred to as plugs, bushings, grommets, and cable connectors, and designed primarily for protecting wiring, cable, tubing or rods passing through a sheet metal panel.
The device usually comprises a plug or bushing which passes through a hole or aperture in the panel, and provided with tabs or locking fingers for locking the plug or bushing to the panel.
In some cases, the bushing or plug is provided with a flexible web having a central aperture for passage therethrough of wires, cables, or tubes of different diameters, and a series of circumferentially-spaced slits which extend radially from said aperture. The portions of the web between the slits provide tongues which flex to accomodate such wires of different diameters.
In using such bushings or plugs, air leakage occurs through or along the slits, as well as at the areas engaged by the locking tabs.
Where such devices are used in connection with the fire wall of an automobile, and holes are drilled in the fire wall for passage therethrough of the suction and liquid lines, or conduits of the air conditioning system of the automobile, they protect the lines or conduits from being damaged or cut by the sharp edges of the holes, but serve little or no purpose in providing an air-tight seal in the fire wall between the engine compartment and the passenger compartment of the automobile. The provision of an air-tight seal at these points is of paramount importance in order to prevent the noxious or undesirable atmosphere in the engine compartment from entering the passenger compartment.